<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .n1{
            color:red;
        }
        .n2{
            background-color: green;
        }
    </style>
</head>
<body>
    <div class="n1">111</div>
    <div class="n1 n2">222</div>
    <div>333</div>
    <div>444</div>
    <div>555</div>
    <div>666</div>
</body>
</html>